To run the game on ultra takes a processor that can run 3 to 4 cores at 4 Ghz. The game is very CPU intensive, and the more you load on your cpu, the worse your performance will be.

We are working to make the game less cpu intensive, but Ultra will still remain for super fast processors. Set your settings to medium or high, and playing with the detail slider will change the average amount of draw calls in any given scene (which is what currently makes our game CPU intensive)